LMNA Mutations G232E and R482L Cause Dysregulation of Skeletal Muscle Differentiation, Bioenergetics, and Metabolic Gene Expression Profile

Abstract

Laminopathies are a family of monogenic multi-system diseases resulting from mutations in the LMNA gene which include a wide range of neuromuscular disorders. Although lamins are expressed in most types of differentiated cells, LMNA mutations selectively affect only specific tissues by mechanisms that remain largely unknown. We have employed the combination of functional in vitro experiments and transcriptome analysis in order to determine how two LMNA mutations associated with different phenotypes affect skeletal muscle development and metabolism. We used a muscle differentiation model based on C2C12 mouse myoblasts genetically modified with lentivirus constructs bearing wild-type human LMNA (WT-LMNA) or R482L-LMNA/G232E-LMNA mutations, linked to familial partial lipodystrophy of the Dunnigan type and muscular dystrophy phenotype accordingly. We have shown that both G232E/R482L-LMNA mutations cause dysregulation in coordination of pathways that control cell cycle dynamics and muscle differentiation. We have also found that R482/G232E-LMNA mutations induce mitochondrial uncoupling and a decrease in glycolytic activity in differentiated myotubes. Both types of alterations may contribute to mutation-induced muscle tissue pathology.

Defining and identifying satellite cell-opathies within muscular dystrophies and myopathies

“…Lmna- null myoblasts also differentiate poorly, and overexpression of pathogenic missense Lamin variants in healthy myoblasts reduces both proliferation and fusion ability despite increased expression of both fusogens Mymk and Mymx [ 122 ], suggesting that Lamin A/C deficiency alters satellite cell function. Fewer myonuclei are found in Lmna- null mice, indicating poor myoblast fusion, correlating with altered satellite cell number [ 94 , [123] , [124] , [125] , [126] , [127] ].…”

Cultured Myoblasts Derived from Rat Soleus Muscle Show Altered Regulation of Proliferation and Myogenesis during the Course of Mechanical Unloading

“…As a rule, stem cell proliferation rate decreases as cells enter a differentiation stage, and altered coordination in the regulation of proliferation/differentiation balance can serve as one of the markers of skeletal muscle wasting [ 10 , 12 ]. Therefore, we have tested if spontaneous myogenic commitment was activated in the HS1 and HS7 myoblast cultures.…”

“…Also, a spontaneous reactivation of developmental programs in adult skeletal muscle was detected in regenerating muscles after injury or under pathological conditions such as muscular dystrophy, different types of myopathies or muscle wasting induced by metabolic disorders [ 8 , 9 ]. Therefore, the pathological alterations in the functional properties of SCs in atrophying muscle are relatively well described for skeletal muscle myopathies of different genesis [ 2 , 9 , 10 , 11 , 12 ], but not for muscle atrophy caused by mechanical unloading/simulated microgravity.…”

Skeletal Muscle Mitochondria Dysfunction in Genetic Neuromuscular Disorders with Cardiac Phenotype

“…Recently, our group, using functional and transcriptomic analysis, have discovered distinct bioenergetic changes in C2C12 myogenic cells harboring lentiviral G232E and R482L LMNA mutations, linked to different types of laminopathies associated with EDMD and FPLD, respectively [ 112 ]. Both mutations had an uncoupling effect on mitochondrial respiration in differentiated myotubes and caused an increase in proton leak, which indicate a decreased efficiency of oxidative phosphorylation.…”